iphone development - UIRotationGestureRecognizer (Clockwise & counter Clockwise detection)?

Question

Is there a way to detect if the rotation done by the user is in clockwise or counter clockwise direct???

I searched for that but couldn't find an answer !

My code looks like this:

 UIGestureRecognizer *recognizer;
 recognizer = [[UIRotationGestureRecognizer alloc] initWithTarget:self action:@selector(spin)];
 [self.rotating addGestureRecognizer:recognizer];
 [recognizer release];

Answer 1

the rotation property will tell you the rotation in radians. A negative value would indicate the rotation is clockwise, and a positive value indicates counter-clockwise.

Example:

UIGestureRecognizer *recognizer;
recognizer = [[UIRotationGestureRecognizer alloc] initWithTarget:self action:@selector(spin:)];  // <-- Note the colon after the method name
[self.rotating addGestureRecognizer:recognizer];
[recognizer release];

- (void)spin:(UIGestureRecognizer *)gestureRecognizer {
    CGFloat rotation = gestureRecognizer.rotation;
    if (rotation < 0) {
        // clockwise
    } else {
        // counter-clockwise
    }
}